Fluid coupling

Abstract

A fluid coupling includes a cover, an impeller, a turbine, an output hub, a lock-up piston, and a wall member. The impeller is fixed to the cover. The turbine is disposed opposite to the impeller. The output hub outputs a torque transmitted thereto from the turbine. The lock-up piston is disposed between the cover and the turbine. The lock-up piston is disposed to be axially slidable on the output hub. The lock-up piston is configured to be engaged by friction with the cover. The wall member is attached to the output hub. The wall member defines a hydraulic chamber in cooperation with the lock-up piston.

What is claimed is: 
     
         1 . A fluid coupling comprising:
 a cover;   an impeller fixed to the cover;   a turbine disposed opposite to the impeller;   an output hub configured to output a torque transmitted thereto from the turbine;   a lock-up piston disposed between the cover and the turbine, the lock-up piston disposed to be axially slidable on the output hub, the lock-up piston configured to be engaged by friction with the cover; and   a wall member attached to the output hub, the wall member defining a hydraulic chamber in cooperation with the lock-up piston.   
     
     
         2 . The fluid coupling according to  claim 1 , further comprising:
 a damper device configured to transmit the torque from the lock-up piston to the output hub therethrough, wherein   the damper device includes
 an input plate configured such that the torque is transmitted thereto from the lock-up piston, 
 first and second output plates disposed to axially interpose the input plate therebetween, the first and second output plates attached to the output hub, and 
 an elastic member elastically coupling the input plate and the first and second output plates, and 
   at least one of the first output plate or the second output plate serves as the wall member.   
     
     
         3 . The fluid coupling according to  claim 2 , wherein
 the first output plate is disposed axially between the lock-up piston and the input plate,   the second output plate is disposed axially between the turbine and the input plate, and   the second output plate serves as the wall member.   
     
     
         4 . The fluid coupling according to  claim 3 , wherein
 the first output plate includes a first bulging portion axially bulging along a shape of the elastic member,   the second output plate includes a second bulging portion axially bulging along the shape of the elastic member,   the first bulging portion is axially opened at an apex thereof, and   the second bulging portion is axially closed at an apex thereof.   
     
     
         5 . The fluid coupling according to  claim 2 , wherein
 the first output plate is disposed axially between the lock-up piston and the input plate,   the second output plate is disposed axially between the turbine and the input plate, and   the first output plate serves as the wall member.   
     
     
         6 . The fluid coupling according to  claim 5 , wherein
 the first output plate includes a first bulging portion axially bulging along a shape of the elastic member,   the second output plate includes a second bulging portion axially bulging along the shape of the elastic member,   the first bulging portion is axially closed at an apex thereof, and   the second bulging portion is axially opened at an apex thereof.   
     
     
         7 . The fluid coupling according to  claim 1 , wherein
 the lock-up piston includes a disc portion and a cylindrical portion, the cylindrical portion axially extending from an outer peripheral end of the disc portion, and   the wall member extends from the output hub to the cylindrical portion.